Help with oscillation and plotting

Hey!

I am finished with a and b but i need much help with c. Down below is my script for a and b but i do not know where to start with c. Could someone please help me with the script for c because i am going on funeral tommorrow and i should be finished on monday morning...?

%% Exercise 2.a

clear

clf

clc

k=1

L=6

x=linspace(0,L);

fplot(@(x) (((2.*k)./L).*x), [0,(L/2)])

hold on

fplot(@(x) (((2.*k)./L).*(L-x)), [(L/2),L])

%% Exercise 2.b

clear

clf

clc

k=1;

L=6;

T=10;

x=linspace(0,L,100); t=linspace(0,T,100);

n=1:100;

for i=1 : length(x)

for j=1 : length(t)

u(i,j)=(8/(pi^2)).*sum((1./(n.^2)).*sin(n.*pi/2).*cos(n.*pi.*t(j)/6).*sin(n.*pi.*x(i)/6));

end

end

surf(t,x,u)

xlabel('t'); ylabel('x'); zlabel('u')

title('Exercise 2.b');

%% Exercise 2.c